Studies on the cereal ecosystem.

Abstract

The chapter discusses the cereal ecosystem. Agricultural productivity is much greater than formerly, however cereal yields, even today, are affected by many factors outside direct human control. Cereal ecosystems are very complex and dynamic, and many new and important biological processes are discussed in this chapter. The changes described in this chapter, especially plant breeding and mechanization, have increased yields in historical times. Pesticide and agrochemical inputs generally have continued to increase exponentially, so that yields appear to have reached an asymptote. It seems therefore that many changes in crop husbandry must have been counterproductive. The abundance of cereal aphids may often be affected by predation. The predators in this case are generalized versatile polyphagous species rather than aphid specialists. The chapter is a preliminary exploration of some of the issues in relation to the changes in contemporary arable farming. The ability to forecast future events will, in part, be determined by the stability of the system from which the projection is to be made and also by knowledge of the processes in that system.